Advances in cardiac surgery have enabled open heart and less-invasive methods for a wide variety of cardiac surgical procedures such as heart valve replacements or repairs. In many of these procedures, it is often necessary to retract tissue and bones in order to provide access to a surgical site. For example, in a sternotomy, where a vertical inline incision is made along the sternum, after which the sternum is divided or “cracked”, a large sternum retractor is used to force the cracked sternum apart, providing access to the heart. Such sternum retractors have jaws which open in a single plane. While a sternotomy provides excellent access to the heart, the procedure is highly invasive and is associated with a high degree of post-operative pain and long recovery times for patients.
With advances in minimally invasive cardiac approaches, surgeons have been able to move away from sternotomies for many procedures. For example, one favored approach to access the heart is to use a right anterior thoracotomy (a much smaller incision in the chest wall). The thoracotomy is often made between two adjacent ribs, and it is often necessary to spread those ribs apart to create an access window for the surgery. This can be done with a smaller version of the single plane style retractor, or, in some cases, with hand-pulled retractors. Hand-pulled retractors require an extra person's pair of hands, which may crowd the operating area around the patient. Hand retractors are also difficult to maintain in an open position over an extended period of time. Therefore, a mechanical rib retractor may be favored over the hand-retractors, since it provides steady, sustained retraction and may reduce operator fatigue and even the need for an additional person in the operating room.
Unfortunately, traditional thoracotomies, made through adjacent ribs, often do not provide enough access for certain types of cardiac procedures. While surgical instruments such as fiber optic scopes, forceps, cutting tools, and suturing tools may fit relatively well through a thoracotomy between adjacent ribs, replacement heart valves and their holders often do not (even when the adjacent ribs are spread apart with existing retractors). As a result, for many cardiac procedures, the thoracotomy often requires resection or removal of ribs in order to provide additional room for larger items, such as a replacement heart valve. While transection with or without reattachment of a rib can be less traumatic than a sternotomy, it would still be desirable to avoid excessive rib mobilization in order to provide less post-operative pain and quicker recovery times for patients.
Several other types of rib retractors have been developed in order to try to provide a larger access space between adjacent ribs. Before describing these retractors, however, it is helpful to consider different orientations of human anatomy so that the motion and operation of the retractors can be compared and contrasted according to how they move relative to the anatomy. Three anatomical planes divide the body into different sectors. The sagittal plane divides the body into a left portion and a right portion. The coronal plane divides the body into an anterior (front) portion and a posterior (back) portion. The transverse plane divides the body into an upper portion and a lower portion. A direction towards the head may generally be referred to as a cephalad direction, while a direction towards the lower end of the spine may generally be referred to as a caudad direction. Therefore, an axis running approximately in a direction from the head towards the lower portion of the body could be referred to as a substantially cephalad-caudal axis. Similarly, an axis running approximately in a direction from the back of the body to the front of the body could be referred to as a substantially anterior-posterior axis.
U.S. Pat. No. 5,865,731 discloses a surgical retractor that “is able to form an oblique tunnel-like opening at an incision site wherein, in addition to spreading the sides of the site incision substantially parallel to the contour of the patient's body, the '731 surgical retractor additionally spreads the incision sides so that one side is depressed toward the patient and the other is directed outwardly from the patient.” However, the rotational or offset positions for the grips must be predetermined before use since only one amount of anterior-posterior movement is possible during use. Furthermore, there is no spreading of the ribs in a cephalad-caudal direction without also having anterior-posterior separation. This may be undesirable since the additional anterior-posterior separation (and its resultant stress on the ribs) may not be needed for the entire duration of an operation.
U.S. Pat. No. 6,159,231 discloses a retractor having two racks movably attached at a nonlinear angle. When the first rack section is horizontally disposed, the other rack section is angled relative to the horizontal plane. The retractor may be ratcheted apart to spread adjacent ribs in a cephalad-caudal direction. One end of the retractor may also be lifted to spread the ribs in an anterior-posterior direction. The lifted end, however, must be held by hand or attached to a cable anchored to a support over the patient in order to maintain the anterior-posterior separation. This either requires additional personnel in the operating room, or modifications to the operating table/ceiling, neither of which is desirable as the additional equipment may get in the surgeon's way.
European Patent 792,620 discloses several embodiments of a rib retractor having adjustments to spread adjacent ribs in a cephalad-caudal direction. These retractors also have an adjustment to lift one rib relative to the other by contacting the patient somewhere else besides the ribs to create a fulcrum point for lifting leverage. Unfortunately, this retractor may be difficult to use on obese patients and is not simple to adjust and lock in place in general.
European Patent 792,620 also discloses a version of a rib retractor where the spreader is attached to the operating table or to some platform which can be slid beneath the patient. This rib retractor has adjustments for both anterior-posterior separation as well as cephalad-caudal separation. While this embodiment alleviates the unnecessary bruising of previous models, its external anchoring system is also complex, cumbersome, and difficult to reposition.
European Patent 792,620 further discloses an embodiment of a rib retractor which spreads the ribs in a cephalad-caudal direction while simultaneously spreading the ribs in an anterior-posterior direction. However, like other examples from the prior art, there is no way to fine tune the opening, or to have one type of separation without the other, if desired, for a portion of the operation with this one retractor.
U.S. Pat. No. 6,416,468 discloses a rib retractor which can generate cephalad-caudal separation of the ribs, as well as an uneven amount of anterior-directed lift on the adjacent ribs. The '468 retractor has no opposing anterior-posterior rib movement. Furthermore, the '468 device employs a pivot point placed against the patient's body, somewhere in addition to the rib contact points, which can result in further bruising and discomfort.
Therefore, there is a need for an improved surgical rib retractor which can provide for varying and controlled amounts of rib separation in both a cephalad-caudal direction as well as an anterior-posterior direction.